Add artists::list_in_library

Artists with at least one wanted item, the same rule the web library
list uses.

src/queries/artists.rs

@@ -1,8 +1,9 @@
 use chrono::Utc;
-use sea_orm::sea_query::Expr;
+use sea_orm::sea_query::{Expr, Query};
 use sea_orm::*;
 
 use crate::entities::artist::{self, ActiveModel, Entity as Artists, Model as Artist};
+use crate::entities::wanted_item;
 use crate::error::{DbError, DbResult};
 
 pub async fn upsert(
@@ -93,6 +94,25 @@ pub async fn list(db: &DatabaseConnection, limit: u64, offset: u64) -> DbResult<
         .await?)
 }
 
+/// Artists that belong in the library: those with at least one wanted item.
+/// An artist without one only exists because a track wanted under another
+/// artist was credited to them (a feature, a collaboration, or a bad match).
+pub async fn list_in_library(db: &DatabaseConnection) -> DbResult<Vec<Artist>> {
+    Ok(Artists::find()
+        .filter(
+            artist::Column::Id.in_subquery(
+                Query::select()
+                    .column(wanted_item::Column::ArtistId)
+                    .from(wanted_item::Entity)
+                    .and_where(wanted_item::Column::ArtistId.is_not_null())
+                    .to_owned(),
+            ),
+        )
+        .order_by_asc(Expr::cust("LOWER(name)"))
+        .all(db)
+        .await?)
+}
+
 pub async fn list_all(db: &DatabaseConnection) -> DbResult<Vec<Artist>> {
     Ok(Artists::find()
         .order_by_asc(Expr::cust("LOWER(name)"))

tests/integration.rs

@@ -458,3 +458,47 @@ async fn test_wanted_find_by_track_id_and_list_by_artist() {
     let no_artist = queries::wanted::list_by_artist(conn, None).await.unwrap();
     assert_eq!(no_artist.len(), 2);
 }
+
+#[tokio::test]
+async fn test_artists_list_in_library() {
+    let db = test_db().await;
+    let conn = db.conn();
+
+    let wanted = queries::artists::upsert(conn, "Kesha", None).await.unwrap();
+    queries::artists::upsert(conn, "Pitbull", None)
+        .await
+        .unwrap();
+    queries::wanted::add(
+        conn,
+        queries::wanted::AddWantedItem {
+            item_type: ItemType::Track,
+            name: "Timber",
+            musicbrainz_id: None,
+            artist_id: Some(wanted.id),
+            album_id: None,
+            track_id: None,
+            user_id: None,
+        },
+    )
+    .await
+    .unwrap();
+    // An item with no artist must not pull in anything
+    queries::wanted::add(
+        conn,
+        queries::wanted::AddWantedItem {
+            item_type: ItemType::Track,
+            name: "Unknown",
+            musicbrainz_id: None,
+            artist_id: None,
+            album_id: None,
+            track_id: None,
+            user_id: None,
+        },
+    )
+    .await
+    .unwrap();
+
+    let listed = queries::artists::list_in_library(conn).await.unwrap();
+    assert_eq!(listed.len(), 1);
+    assert_eq!(listed[0].name, "Kesha");
+}